At the end, all Stephen Hawking had was a twitch. Slowly, over the course of 50 years, his body had shut down — and with it his access to the world. Eventually only a single muscle on his right cheek remained.

By his 76th year, when The Times came to interview him, its movement had become the only reliable link between his great mind and the rest of us.

As we walked into the room one of his carers held up his hand for us to shake. Then that crucial muscle signified that the interview — if the word was not too much of a stretch — had begun.

Visitors to Hawking had to get used to silence. To hear the answer to a single…